HEADS UP: change key binding for swapLeft/Right and IncMaster

The use of arrow keys for swapLeft/Right clash with firefox's back
button. Use the more intuitive mod-shift-jk for this. (It's a movement
operation, after all).

This clashes with IncMaster, so we use mod+comma and mod+period for
these (i.e. the keys mod < and mod > , to move windows to and from the
master area).

While we're here, replace the use of the terms 'left' and 'right' for
navigation, in comments and identifiers, with 'up' and 'down' instead.
Hence mod-j == focusDown. Far more intuitive for people (dons) who live
in fullscreen mode and have vim movement wired into their central
nervous system.

Principle of least VI surprise: movement down or up means using j and k.

darcs-hash:20070526111453-9c5c1-3242145ee5b51eb070a7dc3663f0d6cc01671d5c

1 files changed, 48 insertions, 43 deletions

diff --git a/StackSet.hs b/StackSet.hs
index f6af748..cae577c 100644
--- a/StackSet.hs
+++ b/StackSet.hs
@@ -76,9 +76,9 @@
 --
 module StackSet (
         StackSet(..), Workspace(..), Screen(..), Stack(..),
-        new, view, lookupWorkspace, peek, index, focusLeft, focusRight,
-        focusWindow, member, findIndex, insertLeft, delete, shift,
-        swapMaster, swapLeft, swapRight, modify -- needed by users
+        new, view, lookupWorkspace, peek, index, focusUp, focusDown,
+        focusWindow, member, findIndex, insertUp, delete, shift,
+        swapMaster, swapUp, swapDown, modify -- needed by users
     ) where
 
 import Data.Maybe   (listToMaybe)
@@ -91,10 +91,10 @@ import qualified Data.List as L (delete,find,genericSplitAt)
 --  view,
 --  index,
 --  peek,                   -- was: peek/peekStack
---  focusLeft, focusRight,  -- was: rotate
---  swapLeft, swapRight
+--  focusUp, focusDown,  -- was: rotate
+--  swapUp, swapDown
 --  focus                   -- was: raiseFocus
---  insertLeft,             -- was: insert/push
+--  insertUp,             -- was: insert/push
 --  delete,
 --  swapMaster,             -- was: promote/swap
 --  member, 
@@ -131,9 +131,15 @@ data Workspace i a = Workspace  { tag :: !i, stack :: Stack a }
 -- 
 -- A stack is a cursor onto a (possibly empty) window list.
 -- The data structure tracks focus by construction, and
--- the master window is by convention the left most item.
+-- the master window is by convention the top-most item.
 -- Focus operations will not reorder the list that results from
--- flattening the cursor.
+-- flattening the cursor. The structure can be envisaged as:
+--
+--     +-- master:  < '7' >
+--  up |            [ '2' ]
+--     +---------   [ '3' ]
+--  focus:          < '4' >
+--  dn +----------- [ '8' ]
 --
 -- A 'Stack' can be viewed as a list with a hole punched in it to make
 -- the focused position. Under the zipper/calculus view of such
@@ -142,8 +148,8 @@ data Workspace i a = Workspace  { tag :: !i, stack :: Stack a }
 --
 data Stack a = Empty
              | Node { focus  :: !a        -- focused thing in this set
-                    , left   :: [a]       -- clowns to the left
-                    , right  :: [a] }     -- jokers to the right
+                    , up     :: [a]       -- clowns to the left
+                    , down   :: [a] }     -- jokers to the right
     deriving (Show, Read, Eq)
 
 
@@ -247,32 +253,32 @@ index = with [] $ \(Node t l r) -> reverse l ++ t : r
 --
 -- /O(1), O(w) on the wrapping case/. 
 --
--- focusLeft, focusRight. Move the window focus left or
--- right, wrapping if we reach the end. The wrapping should model a
--- 'cycle' on the current stack. The 'master' window, and window order,
+-- focusUp, focusDown. Move the window focus up or down the stack,
+-- wrapping if we reach the end. The wrapping should model a -- 'cycle'
+-- on the current stack. The 'master' window, and window order,
 -- are unaffected by movement of focus.
 --
--- swapLeft, swapRight. Swap the focused window with its left or right
--- neighbour in the stack ordering, wrapping if we reach the end. Again 
--- the wrapping model should 'cycle' on the current stack.
+-- swapUp, swapDown, swap the neighbour in the stack ordering, wrapping
+-- if we reach the end. Again the wrapping model should 'cycle' on
+-- the current stack.
 -- 
-focusLeft, focusRight, swapLeft, swapRight :: StackSet i a s -> StackSet i a s
-focusLeft = modify Empty $ \c -> case c of
+focusUp, focusDown, swapUp, swapDown :: StackSet i a s -> StackSet i a s
+focusUp = modify Empty $ \c -> case c of
     Node _ []     [] -> c
     Node t (l:ls) rs -> Node l ls (t:rs)
     Node t []     rs -> Node x (xs ++ [t]) [] where (x:xs) = reverse rs
 
-focusRight = modify Empty $ \c -> case c of
+focusDown = modify Empty $ \c -> case c of
     Node _ []     [] -> c
     Node t ls (r:rs) -> Node r (t:ls) rs
     Node t ls     [] -> Node x [] (xs ++ [t]) where (x:xs) = reverse ls
 
-swapLeft = modify Empty $ \c -> case c of
+swapUp = modify Empty $ \c -> case c of
     Node _ []     [] -> c
     Node t (l:ls) rs -> Node t ls (l:rs)
     Node t []     rs -> Node t (reverse rs) []
 
-swapRight = modify Empty $ \c -> case c of
+swapDown = modify Empty $ \c -> case c of
     Node _ []     [] -> c
     Node t ls (r:rs) -> Node t (r:ls) rs
     Node t ls     [] -> Node t [] (reverse ls)
@@ -285,7 +291,7 @@ focusWindow :: (Integral i, Eq s, Eq a) => a -> StackSet i a s -> StackSet i a s
 focusWindow w s | Just w == peek s = s
                 | otherwise        = maybe s id $ do
                     n <- findIndex w s
-                    return $ until ((Just w ==) . peek) focusLeft (view n s)
+                    return $ until ((Just w ==) . peek) focusUp (view n s)
 
 --
 -- Finding if a window is in the stackset is a little tedious. We could
@@ -310,34 +316,34 @@ findIndex a s = listToMaybe
 
 --
 -- /O(n)/. (Complexity due to duplicate check). Insert a new element into
--- the stack, to the left of the currently focused element.
+-- the stack, above the currently focused element.
 --
 -- The new element is given focus, and is set as the master window.
--- The previously focused element is moved to the right.  The previously
+-- The previously focused element is moved down.  The previously
 -- 'master' element is forgotten. (Thus, 'insert' will cause a retiling).
 --
 -- If the element is already in the stackset, the original stackset is
 -- returned unmodified.
 --
 -- Semantics in Huet's paper is that insert doesn't move the cursor.
--- However, we choose to insert to the left, and move the focus.
+-- However, we choose to insert above, and move the focus.
 --
-insertLeft :: Eq a => a -> StackSet i a s -> StackSet i a s
-insertLeft a s = if member a s then s else insert
+insertUp :: Eq a => a -> StackSet i a s -> StackSet i a s
+insertUp a s = if member a s then s else insert
   where insert = modify (Node a [] []) (\(Node t l r) -> Node a l (t:r)) s
 
--- insertRight :: a -> StackSet i a s -> StackSet i a s
--- insertRight a = modify (Node a [] []) $ \(Node t l r) -> Node a (t:l) r
+-- insertDown :: a -> StackSet i a s -> StackSet i a s
+-- insertDown a = modify (Node a [] []) $ \(Node t l r) -> Node a (t:l) r
 -- Old semantics, from Huet.
--- >    w { right = a : right w }
+-- >    w { down = a : down w }
 
 --
 -- /O(1) on current window, O(n) in general/. Delete window 'w' if it exists.
 -- There are 4 cases to consider:
 --
 --   * delete on an Empty workspace leaves it Empty
---   * otherwise, try to move focus to the right
---   * otherwise, try to move focus to the left
+--   * otherwise, try to move focus to the down
+--   * otherwise, try to move focus to the up
 --   * otherwise, you've got an empty workspace, becomes Empty
 --
 -- Behaviour with respect to the master:
@@ -353,13 +359,13 @@ delete w s | Just w == peek s = remove s -- common case.
     removeWindow o n = foldr ($) s [view o,remove,view n]
 
     -- actual removal logic, and focus/master logic:
-    remove = modify Empty $ \c -> 
-      if focus c == w 
+    remove = modify Empty $ \c ->
+      if focus c == w
       then case c of
-        Node _ ls     (r:rs) -> Node r ls rs    -- try right first
-        Node _ (l:ls) []     -> Node l ls []    -- else left.
+        Node _ ls     (r:rs) -> Node r ls rs    -- try down first
+        Node _ (l:ls) []     -> Node l ls []    -- else up
         Node _ []     []     -> Empty
-      else c { left  = w `L.delete` left c, right = w `L.delete` right c }
+      else c { up = w `L.delete` up c, down = w `L.delete` down c }
 
 ------------------------------------------------------------------------
 -- Setting the master window
@@ -372,8 +378,7 @@ swapMaster = modify Empty $ \c -> case c of
     Node _ [] _  -> c    -- already master.
     Node t ls rs -> Node t [] (ys ++ x : rs) where (x:ys) = reverse ls
 
- -- natural! keep focus, move current to furthest left, move furthest
--- left to current position.
+ -- natural! keep focus, move current to the top, move top to current.
 
 -- ---------------------------------------------------------------------
 -- Composite operations
@@ -381,13 +386,13 @@ swapMaster = modify Empty $ \c -> case c of
 
 -- /O(w)/. shift. Move the focused element of the current stack to stack
 -- 'n', leaving it as the focused element on that stack. The item is
--- inserted to the left of the currently focused element on that
--- workspace.  The actual focused workspace doesn't change. If there is
--- no element on the current stack, the original stackSet is returned.
+-- inserted above the currently focused element on that workspace.  --
+-- The actual focused workspace doesn't change. If there is -- no
+-- element on the current stack, the original stackSet is returned.
 --
 shift :: (Eq a, Eq s, Integral i) => i -> StackSet i a s -> StackSet i a s
 shift n s = if and [n >= 0,n < size s,n /= tag (workspace (current s))]
             then maybe s go (peek s) else s
-    where go w = foldr ($) s [view (tag (workspace (current s))),insertLeft w,view n,delete w]
+    where go w = foldr ($) s [view (tag (workspace (current s))),insertUp w,view n,delete w]
                            -- ^^ poor man's state monad :-)